1. Field of the Invention
The present invention relates to a displaying apparatus used for a vehicle to project patterns on a half mirror or on a front windshield of the vehicle such that a driver of the vehicle may see the patterns overlapping outside views.
2. Description of the Prior Art
Generally in a vehicle, indicators such as a speedometer and a clock are disposed on a dashboard such that a driver of the vehicle directly see patterns displayed on the indicators.
Also, there is a so-called headup displaying apparatus which has been recently developed to project patterns on a half mirror or on a front windshield of the vehicle such that the driver see the projected patterns (virtual images) overlapping outside views. The headup displaying apparatus is adequate for the safety driving because the driver can see the patterns without changing his eyes during the driving.
FIG. 1 shows an example of the headup displaying apparatus for a vehicle according to a prior art. In the figure, a dashboard 1 incorporates a projector 105 which comprises a display device 102, a light source 103, lens 104, etc. The display device 102 is constituted with, for instance, liquid crystal cells. Light irradiates the back of the display device 102, and a pattern to be displayed of the display device 102 is enlarged with the lens 104 and projected on a half mirror 101. The half mirror 101 reflects a virtual image 107 of the pattern toward a driver 8.
According to this displaying apparatus of the prior art, the projector 105 including the display device 102 is received in the dashboard 1 which is usually occupied by various instruments and wiring so that a limited space remains for the projector 105. Therefore, the dashboard 1 shall be designed to be sufficiently large to accommodate the projector 105 in the dashboard 1, thus reducing an interior space of the vehicle.
Further, through an opening formed on the top surface of the dashboard 1 to project a pattern as shown in FIG. 1, strong sun light passing through a front windshield is made incident to the projector 105 to destroy the display device 102 composed of the liquid crystal cells.
To direct the virtual image 107 on the half mirror 101 toward the driver 8 who is sitting in a particular posture and having a particular physical constitution, as illustrated in FIGS. 2a and 2b the half mirror 101 is rotated in a right-and-left direction around a vertical axis Y and in a back-and-forth direction around a horizontal axis X to adjust an angle of the half mirror 101. After adjusting the half mirror 101, thumbscrews fitted to the horizontal and vertical axes X and Y respectively are tightened to fix the axes. Namely, the two thumbscrews shall be manipulated before and after the adjustment so that the adjusting operation is bothersome, the number of parts increased, the apparatus as a whole complicated, long time and many processes required for manufacturing and assembling the apparatus, and the cost increased.